[60]Fullerene cycloaddition across hindered acenes

Abstract

The Diels–Alder cycloadditions of [60]fullerene across sterically hindered 6,13-bis(2′,6′-dialkylphenyl)pentacenes, 1 and 2, produce fullerene–acene monoadducts 3 and 4. In both cases, further [60]fullerene cycloaddition to form cis-bis[60]fullerene adducts is retarded by steric resistance between the [60]fullerene moieties and the o-dialkyl substituents. Instead, the fullerene moieties of monoadducts 3 and 4 sensitize the formation of ¹O₂ which subsequently cycloadds across the acene backbone to produce novel syn and anti [60]fullerene–dioxo bisadducts, 8–11.